Opening a compiled help .chm file and looking at the index causes a .chw file to be created adjacent to the .chm file. This new file causes the calculated hash of the toolchain to be different from what's expected and things go downhill from there.

Perhaps we can exclude .chw files in the same manner we ignore symbol cache directories and crash logs? Or maybe the script should only care about files that existed in the original archive and ignore any new files?